9 official rulings from Bandai, last ruled Aug 1, 2024. Straight answers to how this card actually resolves.

What does "declare 1 card category" in this card's <Start Opp Turn> effect mean, exactly?
It refers to the four card categories: Digi-Egg cards, Digimon cards, Tamer cards, and Option cards. You declare 1 of these categories at the start of your opponent's turn for this card's effect, your opponent reveals the top card of their deck, and if the revealed card is in the declared category, this Digimon will be unaffected by effects from cards in the declared card category.
Ruled Mar 28, 2024
Can I use this card's <When Digivolving> effect to return my [EX2-007]/[Mother D-Reaper] from the battle area to the security stack, reveal all cards in my opponent's security stack, and place 1 card among them at the top of my opponent's deck?
Yes, you can. If your [EX2-007]/[Mother D-Reaper] is chosen as the target to place in the security stack, it will ultimately be placed at the bottom of the Digi-Egg deck instead of the security stack according to the rules, but it meets this card's "by placing 1 Digimon on top of its owner's security stack" condition. A card isn't actually added to the security stack, therefore effects such as "when a card is added to the security stack" don't trigger.
Ruled Mar 28, 2024
Can I use this card's <When Digivolving> effect to return my token played as a Digimon from the battle area to the hand, reveal all cards in my opponent's security stack, and place 1 card among them at the top of my opponent's deck?
Yes, you can. If your token is chosen as the target to place in the security stack, it will ultimately be removed from the game instead of being placed in the security stack according to the rules, but it meets this card's "by placing 1 Digimon on top of its owner's security stack" condition. A card isn't actually added to the security stack, therefore effects such as "when a card is added to the security stack" don't trigger.
Ruled Mar 28, 2024
If I choose my [EX2-007]/[Mother D-Reaper] or token that is treated as a Digimon in the battle area as the target for this card's <When Digivolving> effect, it isn't placed in the security stack. In such cases, do "when a card is removed from the security stack" effects trigger because a card wasn't added to the security stack even though it normally should have been added?
No, it doesn’t trigger.
Ruled Mar 28, 2024
I declared Tamer cards for this card's <Start Opp Turn> effect, and a Tamer card was revealed from the deck. In such cases, is this Digimon unaffected by inherited effects on Tamer cards in digivolution cards of my opponent's Digimon?
No, it's affected by such effects. Inherited effects on Tamer cards in digivolution cards of Digimon are treated as Digimon effects.
Ruled Mar 28, 2024
I declared Digimon cards for this card's <Start Opp Turn> effect. If a Digimon card is revealed from the deck, is this Digimon unaffected by <Security> effects activated by Security Digimon?
Yes, it isn't affected. <Security> effects on Security Digimon are treated as Digimon effects, so the "this Digimon isn't affected by the effects of your opponent's Digimon" effect prevents such effects from affecting this Digimon.
Ruled Mar 28, 2024
Can this card's [Start of Opponent's Turn] effect declare card categories that do not go into the deck, such as Digi-Egg cards?
Yes, it can be declared.
Ruled Aug 1, 2024
Due to this card's [Start of Opponent's Turn] effect, this card is no longer affected by Digimon effects. At this time, is this card not affected by the effects of my other Digimon?
Yes, it is not affected by them.
Ruled Aug 1, 2024
Due to this card's [Start of Opponent's Turn] effect, this card no longer gets Digimon effects. At this time, does it no longer get the inherited effects of Digimon cards in this card's digivolution sources?
No. It gains inherited effects.
Ruled Aug 1, 2024
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Questions and answers are Bandai's official rulings, collected and translated by the DigimonCardGame Wiki community and reused here under CC BY-SA. Card names and card text are © their respective publishers; Combalo is not affiliated with Bandai.